In the past, it has been common practice to utilize a purified water reservoir that contains a confined space filled with air, with air in the confined space being compressed as purified water discharges into the reservoir. The compressed air serves as the motive force to discharge purified water from the reservoir when purified water is required. This type of reservoir has the operational disadvantage that as the reservoir fills with purified water, an increasing back pressure is placed on purified water discharging from the reverse osmosis cartridge, and as a result cannot be used efficiently in areas where the feed water to be purified is supplied at a relatively low pressure. This type of reservoir even in areas where the feed water is at a substantial pressure does not operate efficiently due to the back pressure exerted by the compressed air on purified water discharging from the reverse osmosis cartridge, and the efficiency decreasing as the reservoir fills with purified water.
In another form of prior art reservoir, the purified water reservoir is an elongate fiber wound vessel that has the interior divided by a pliable barrier into first and second longitudinal compartments of variable volume, with one compartment containing purified water, and the other compartment capable of receiving pressurized feed water or reject water to discharge purified water from the reservoir. Certain prior art reverse osmosis systems that employ such reservoirs have the operational disadvantage that after the purified water has remained in the reservoir for a prolonged period of time, the purified water becomes contaminated due to osmosis occurring between the purified water and feed water in the reverse osmosis cartridge. Discharge of reject water or feed water to the reservoir in this type of assembly is controlled by complicated hydraulically operated means that are responsive to the pressure of the purified water. Fiber wound reservoirs are formed as an integral unit, and are not capable of being arranged to utilize the same pliable barrier when the overall volume of the reservoir is halved as is possible with Applicant's reservoir. Also, reservoirs of this type utilize a pliable barrier that is of substantially the same length as the interior of the reservoir, in contrast to Applicant's barrier that is only one half the length for a reservoir of the same volume. In other forms of prior art reverse osmosis assemblies of the above described type, excess purified water is discharged from the reservoir to a drain after the reservoir has been filled.
A major object of the present invention is to provide an inexpensive purified water reservoir of simple design, one that may be easily disassembled to permit the interior thereof to be cleaned, preferably utilizes major components that may be injection molded from a suitable commercially available polymerized resin, employs a pliable barrier to subdivide the interior of the reservoir into first and second confined spaces of variable volume into and out of which purified water and reject or feed water may flow through passages in the reservoir, and on that substantially eliminates the possibility of leakage due to flanges on the major components including the pliable barrier being gripped with a desired force by a circumferentially extending clamp that may be manually tensioned to a desired degree.
Another object of the invention is to supply a purified water reservoir in which the major components are a pair of cup shaped bodies that have first circular flanges that extend outwardly therefrom in abutting contact with a second circular flange that extends outwardly from the pliable barrier that is cup shaped, with the first pair of flanges and the second flange situated therebetween being gripped by a circular flange to provide a reservoir of a desired first interior volume, and this volume being reduced to substantially one half while using the same barrier by substituting a circular closure plate for one of the cup shaped bodies.
Yet another object of the invention is to supply a reservoir that not only serves to store purified water in a reverse osmosis system, but also provides a mounting for a valve assembly that is responsive to the movement of the barrier by physical contact, therewith with the valve assembly serving to reduce the rate of flow of feed water to the reverse osmosis cartridge as the reservoir approaches a filled condition with purified water, and as a result a substantial saving being achieved in the volume of feed water consumed over a period of time relative to prior art reverse osmosis devices is achieved.
A still further object of the invention is to furnish a purified water reservoir that permits a reverse osmosis cartridge to operate at optimum efficiency as the only back pressure to which purified water discharging from the cartridge is that due to the weight of feed water or reject water in the second confined space above the first confined space, and this weight decreasing as the first confined space fills with purified water.